U.S. Pat. Nos. 3,212,582, 3,234,723, 3,486,557 and 4,205,926 disclose sucker rods with metal wires or cables encased in plastic. U.S. Pat. No. 4,024,913 discloses a sucker rod with synthetic polymer fibrous rovings encased in plastic. U.S. Pat. No. 3,034,566 discloses apparatus for making glass fiber reinforced plastic rods.
U.S. Pat. No. 3,889,579 discloses glass fiber reinforced plastic sucker rods, both solid and hollow. In column 4, the desirability of semi-rigidity for the sucker rods is disclosed, the capability of being bent being limited to a radius of curvature of as great as 15 or 20 feet, and typically greater than 6.5 or 7 feet. This results in "very large reels" (col. 4, line 23) when the rod is wound. Such very large reels are difficult to handle and transport.